Study On The Application Of Low Impact Development Technology In The Block Of Shenzhen

Taking the low carbon town of Shenzhen as the background, restorative effect oflow impact development technology on the water recycle was mainly stu died in thisresearch.A block in the low carbon town was selected as the study area, and the stormwater management model was used to simulate the water recycle.The constructionmodes of block were classified into three kinds，current land mode, conventionaldevelopment mode and low impact development mode, which could reflect the effectof low impact development technology. According to the types of land in this area,theparameters of the models were initially assigned and the accuracy of this value shouldbe calibrated. The subcatchment basin were divided by the drainage area and thedrainage network were made into models by existing data in this research.Both Theannual total runoff and the peak flow of runoff were taken as the quantitative index torepresent water recycle of the study area. Firstly, the objective of this research isdetermind by the comparsion of the simulated outcomes of current land mode andconventional development mode.Then, Some appropriate low impact developmentfacilities were selected, such as green roofs, rain garden, permeable pavement andsunken green space，which to build low impact development model.The control ratioof the low impact development facilities has been changed to make the water cycle oflow impact development construction closest to the current construction.The conclusions can be drawn from the results of the research：1. By the conventional development, the annual total runoff increased by105%,andthe annual peak flow rate increased by72%, while the annual total infiltration ofrain water reduced52%in the study area.These mainly due to the generaldevelopment that causes the change in the type of underlying surface and theincreases the proportion of impervious underlying surface.2. By adding low impact facilities into impervious surface of100%，the annual totalrunoff and the peak flow of runoff are cut down greatly. Since the initial assignmentis too large, the result is far smaller than the current model,which doesn’t conformto the research object and should be optimized.3. After optimization, the total annual runoff is almost the same as the current value,and the annual peak flow of runoff is slightly more than the current.It is illustratedthat the annual runoff of construction is not larger than before can be achieved by the low impact development facilities in the study area.4. Eventually，the best control ratio of the low impact development facilities on theimpermeable pavement shows that，in the study area green roofs account for8.82%,permeable pavement accounts for14.60%,concave down Green accounts for3.01%,rain garden accounts for4.05%,low impact development tree pool accountsfor0.46%.Low impact development facility totally accounts for about31%in thearea.